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1   /*
2    * Copyright 2002,2004 The Apache Software Foundation.
3    *
4    * Licensed under the Apache License, Version 2.0 (the "License");
5    * you may not use this file except in compliance with the License.
6    * You may obtain a copy of the License at
7    *
8    *      http://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS,
12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   * See the License for the specific language governing permissions and
14   * limitations under the License.
15   */
16  
17  package org.apache.commons.jelly.tags.define;
18  
19  import org.apache.commons.jelly.JellyTagException;
20  import org.apache.commons.jelly.TagSupport;
21  import org.apache.commons.jelly.impl.DynamicTagLibrary;
22  
23  /***
24   * An abstract base class useful for implementation inheritence.
25   *
26   * @author <a href="mailto:jstrachan@apache.org">James Strachan</a>
27   * @version $Revision: 155420 $
28   */
29  public abstract class DefineTagSupport extends TagSupport {
30  
31      // Implementation methods
32      //-------------------------------------------------------------------------
33  
34      /***
35       * @return the current dynamic tag library instance or throws a JellyException
36       * if one is not available
37       */
38      protected DynamicTagLibrary getTagLibrary() throws JellyTagException {
39          TaglibTag tag
40              = (TaglibTag) findAncestorWithClass(TaglibTag.class);
41          if ( tag == null ) {
42              throw new JellyTagException( "<define:tag> must be inside <define:taglib>" );
43          }
44          return tag.getTagLibrary();
45      }
46  
47  }